Roadmap to Precision 3D Printing of Cellulose: Rheology‐Guided Formulation, Fidelity Assessment, and Application Horizons

ABSTRACT The translation of cellulose nanostructures into functional materials through Direct Ink Writing (DIW) necessitates precise control over multiple length scales, from molecular interactions to macroscopic architectures. This critical review presents a systematic analysis of the fundamental parameters governing the development of high‐performance cellulose‐based inks, establishing quantitative correlations between molecular design, processing conditions, and final material properties. By examining the roles of cellulose nanocrystals (CNC) and cellulose nanofibers (CNF) in developing inks, we demonstrate how surface chemistry and hierarchical assembly direct the rheological behaviour essential for high‐fidelity printing. Our analysis introduces a theoretical framework that correlates viscoelastic properties with printing parameters, enabling control over structural features across multiple length scales. The review establishes clear mechanistic relationships between ink formulation strategies, including concentration optimization and crosslinking mechanisms, and their effects on shape fidelity and structural integrity. Through systematic examination of processing‐structure‐property relationships, we reveal how molecular‐level control translates into tailored mechanical, biological, and electromagnetic properties in printed architectures. These insights provide the foundation for engineering next‐generation cellulose‐based materials, from biomedical scaffolds to functional devices. In brief, the quantitative correlations and design principles presented here advance our fundamental understanding of cellulose‐based ink systems and establish a roadmap for achieving precise control in advanced manufacturing applications.